Burner control system



Aug. 22, 1933 T. cLARKsoN BURNER CONTROL SYSTEM Fild April 6, 1951 2 Sheet s-Sheet 1933- T. CLARKSON BURNER CONTROL SYSTEM Filed April 6, 1931 vlflllI/Illllllllllll 1 III/1,1114 'I/IIIIII 1 Patented Aug. 22, 1933 UNITED STATES PATENT OFFICE BURNER CONTROL SYSTEM Thomas Clarkson, Wilmington, Del. Application April 6, 1931. Serial No. 528,194

9 Claims. (01. 158-455) This invention relates to burner control systems and apparatus therefor, and particularly to automatic control for burners using fluid fuel.

It is a general object of the present invention to provide a novel burner control system and apparatus therefor.

More particularly, it is an object of the invention to provide a system and apparatus wherein a burner using fluid fuel is automatically controlled to maintain substantially constant ratio of fuel to air throughout any load conditions of the burner.

An important feature of the invention resides in the method of and means 'for automatically regulating the quantity of fuel delivered by the burner in accordance with the quantity of air supplied to the burner.

Another important feature of the invention resides in means for automatically maintaining a substantially constant pressure of steam in a boiler fired by a fluid fuel burner by adjusting the quantity of air delivered to the burner in accordance with the steam pressure and by adjusting the quantity of fuel delivered to the burner in accordance with the air pressure at the burner.

A further important feature of the invention resides in adapting a burner of the type described for use where the air supplied thereto is subject to wide variations in pressure resulting from changes in the power supplied to the driving means for the air delivery mechanism.

A still further feature of the invention resides in the provision of automatic control mechanism which insures that air will be delivered to the burner before fuel on starting up, to prevent explosions, and in which the fuel will be shut off prior to the air on stopping.

Other and further features and objects of the invention will be more apparent to those skilled in the art to which this invention pertains, upon a consideration of the accompanying drawings and following specification, wherein is disclosed 5 a single, exemplary embodiment of the invention, with the understanding, however, that such changes and variations may be made therein as fall within the scope of the appended claims without departing from the spirit of the in- 00 vention.

In said drawings:

Figure 1 is a schematic illustration of the necessary assemblage of apparatus for carrying out the system of thepresent invention;

Figure 2 is a longitudinal central section of one type of fuel delivery jet suitable for use with the present invention;

Figure 3 is a; rear face view of the jet tip;

, Figure 4 is a section on line 4-4 of Fig. 1; and

Figure 5 is a view, partly in section, of a modifled form of fuel control valve.

When fluid fuel such as gas or oil is to be burned economically, and to produce as clean a flame as possible, it is essential that the proper fuel-air ratiobe maintained at all times in spite of changes in the capacity of the burner incident to changes in the demand for heat. The present invention contemplates automatic regulation of the quantity of fuel delivered in accordance with the quantity of air which is delivered for mixture therewith to promote the combustion. v

In operating a fluid fuel burner, and particularly where the fuel is liquid, it is highly essential that the air be turned onprior to the fuel and ignition when starting up the burner so as to insure an effective scavenging of the boiler or other heatedparts of any oil fumes which may have remained from a previous firing, for otherwise explosions might result. Also, on shutting down the burner, it is important that the flow of fuel be stopped prior to the flow of air, for this insures the removal of fumes and products of combustion and permits some slight cooling of the parts by the cool air. The present invention provides automatic and fool-proof mech" anism for insuring the proper sequence of operations on starting and stopping.

The invention is illustrated for the sake of convenience only and in no wise in a limiting sense, in conjunction with a steam boiler or water heater of the type disclosed in my Patent No. 1,755,949, granted April 22, 1930, and particularly for use on board locomotives of the electric or so-called gas-electric type for the production of steam for car heating. On such locomotives it has been found that there is a wide variation in the voltage of the current available resulting from changes in load, speed, grade, etc., and that consequently the electric motor which drives the fan or other delivery device for the air which is mixed with the fuel on burning does not have a constant speed so that the quantity. of air delivered is not constant. In order to maintain clean and economical combustion, it is necessary to maintain the proper air-fuel ratio. Where all is used and dependent on the type thereof, it is found that from 22 to 30 pounds of air are required per pound of oil.

Referring now to the drawings for a more complete disclosure of the invention, there is shown at 10 a steam generator or water heater of the type disclosed in the patent hereinbefore mentioned and which is provided at 11 with a liquid fuel injection device to which fuel is de livered under a substantially constant pressure of say 200 pounds per square inch through the pipe 12 from the oil pump 12'. This nozzle 11 atomizes the fuel without the use of air or steam and delivers it in a conical spray into the interior of the tube 13.

Air for supporting the combustion of the oil is delivered from the duct 14 into the substantially annular chamber 15 and passes through the radial passage 16 into the chamber 1'7 surrounding the perforated cone 18 at the upper end of the tube 13. Most of the air for combustion is delivered through the perforations in this cone where it mingles with the atomized fuel. The products of combustion are directed downwardly through the tube 13, reverse themselves against the lower wall 19 of the inner shell of the boiler, pass upwardly around the water thimbles 20 and along the outside of the tube 13, into the annular passage 21 and are vented through the port 22.1eading to a suitable stack.

Air is supplied to the duct- 14 under pressure and comprises a convenient medium for regulating the rate of combustion to maintain a constant steam pressure, for instance, in the boiler, or temperature if it is used as a water heater. The water inlet to the boiler is shown at 23 and the steam outlet at 24 leading to the delivery pipe 25. Tapped off of this delivery pipe is the pipe 26 leading to the regulator mechanism 27 which controls the damper 28 in the duct 14 and hence the quantity of air delivered to the burner.

Conveniently, the regulator mechanism is of conventional form and includes a diaphragm or piston in the housing 27' which is subject to the pressure of the steam in the pipe 26 and opposed by the adjustable spring 29. The piston rod 30 acts through the linkage 31 on the arm 32 which controls the damper valve 28. It will be seen that an increase in steam pressure will move the piston or diaphragm to the right and turn the damper in a closing direction, thus reducing the quantity of air delivered into the annular chamber 15. Since the friction resisting the flow of air into the interior 'of the boiler is substantially constant, 'the pressure will be reduced in the chamber 15. The reverse is true when the steam pressure decreases. These variations in air pressure form a convenient agency for controlling the quantity of oil delivered.

As before mentioned, the oil nozzle is of the type delivering the liquid fuel in an atomized spray without the use of air or steam for the purpose. Conveniently, and as a representative type of burner, has been shown one which is more completely described in the patent to Pea body No. 1,628,424. granted May 10, 1927. In this burner the oil under pressure is supplied to the annular space 33 within the sleeve 34 and is fed through the holes 36 into the annular groove 37 in the rear face of the tip 38 which is secured to the sleeve 34 by the cap member 40.

The tip-member 38 has the central delivery opening 41 therethrough and the frustro-conical chamber 42 in its rear face and this chamber is connected to the annular groove 37 by means of the substantially tangential passages 43. The flat rear face of the tip 38 bears against the flat front face of the insert 46 through which the holes 36 are formed, and it will be seen that as oil is introduced under high pressure into theannular groove 37, it will be driven through the passages 43 tangentially into the atomizing or whirling chamber 42 where it is given a high velocity whirl which causes it to pass out through thetdelivery opening 41 in the form of a fine mis In order that the quantity of oil delivered through 41 can be changed without changing the pressure on the oil deliveredinto the annular space 33 from the pipe 12 and without diminishing the rate of whirl in the chamber 42, there are provided a series of small openings 48 in the member 46 which communicate with the periphery of the whirling chamber 42 and connect it to the by-pass tube or pipe 50 which is coaxial with the tube 34. If this pipe 50 is opened by means of a suitable regulating valve, a regulable quantity of the oil will be delivered from the chamber 42 without passing out through the delivery aperture 41, but all of the oil, and in the same quantity as if the pipe 50 were closed, will enter through the tangential passages 43 so that there will be no diminishing in the atomizing action.

The pipe 50 is seen to leave the rear of the fitting 51 into which the pipe 12 and tube 34 are also connected, and this pipe 50 leads to a suitable control valve mechanism 52.

This mechanism 52 comprises any suitable form of valve. As shown in Figure 4, it may comprise a cylindrical casing in which is arranged a slidable plug 53 prevented from rotation as by the pin and slot arrangement 54 and having an inclined slabbed-ofi portion 55 which cooperates with the port from which the pipe 56 leads to gradually close off this port as the plug 53 is moved toward the right. When the plug is toward the left, a clear passage is open to the discharge pipe 56 which carries away the excess oil and returns it to the fuel tank. The plug 53 is internally threaded and fits on the screw threaded member 57 which has reduced ends 58 journaled in appropriate bearings in the casing ends and held against longitudinal movement so that rotation of the screw will cause longitudinal movement of the plug. Connected to an extension of the screw is the lever arm 60. A cylinder 62 is suitably mounted adjacent the arm 60 and is fitted with a piston 63 biased to the left, as seen in Figure 1, by suitable springs 64 and fitted with a piston rod 65 having the pin and yoke connection 66 with the arm 60. The interior of the cylinder 62 is connected by the pipe 67 with the chamber 15 so that it will be seen that the valve plug 53 is under the control of the air pressure in the chamber 15. As the pressure therein, increases, the piston 63 is moved more and more to the right, and the valve is gradually closed, which causes a greater flow of fuel through the nozzle, to compensate for the increased flow of air produced by the increased pressure. Any reduction in pressure permits a greater relief of oil and a consequent reduction in quantity delivered from the nozzle.

As far as described, it will be seen that two types of control are permitted. First, constant steam pressure or, by obvious changes, constant water temperature is maintained by allowing the steam pressure to control the quantity of air through the agency of the mechanism 27 and damper 28, and the quantity of air in turn atfects the pressure in the chamber 15 and is reflected in the operation of the relief valve plug 53. The whole mechanism is so calibrated that it maintains the proper fuel-air ratio within the range of load variations permitted by the fuel injector nozzle. It will be obvious that where another type of fuel nozzle is used, the direct control of the quantity of fuel delivered thereto can be effected by a mechanism such as-52 operating in a reverse manner.

A second and important type of control is that resulting from a change in the air pressure and quantity, in the duct 14, produced by a change in the voltage of the current supplied to the electric motor which drives the blower or air fan 71. With the reduction in the blower speed the air pressure drops in the chamber 15, and a consequent reduction in the volume of fuel delivered to the combustion chamber results from an increase in the relief flow and vice versa, and a clean flame is always maintained owing to the proper air-fuel ratio, thus preventing sooting of the boiler and similar troubles, as well as conserving fuel.

Where it is desirable to know the approximate steaming capacity of the boiler at various times, there can be conveniently arranged an arcuate scale over which the damper lever 32 moves, and this scale can be graduated,,as shown at '76, in pounds of water evaporated per hour or in any other convenient units so that it can be estimated how much steam is being delivered from the boiler by the position of the arm 32. In cases where it is desirable to limit the maxi= mum or minimum or both quantities of steam.

which may be generated by the burner, stops '77 for maximum and 78 for minimum rate can be provided to be adjustable in the slot 79. These stops can be set as desired to limit the movement of the damper, and for starting purposes under certain conditions the maximum stop can be set to a reduced rate of evaporation to in sure low oil flow until the boiler is well heated The oil pump 12 is of one of thecommon types having a greater capacity at all times than the maximum demand of the nozzle and is provided with a suitable by-pass for the excess oil;

. and for the purposes of this invention a magneto 84 is also driven by this motor and is connected by the high tension lead 85 to the igniter 86 in the burner. The oil pump is of such capacity that sufficient fuel is delivered under any voltage conditions which may exist on the 10- comotive.

As before mentioned, when the burner is started, it is desired that there be air blowing through it before oil is delivered, and for this purpose there is provided a switch 8'7 for closing the electric circuit 88 to the fan motor '70, and this switch is the only means of control for starting and stopping the operation of the burner. To insure that the motor 83 comes into operation after the fanhas started, the circuit 90 thereof is controlled by a switch, of which one arm is the arm 60 actuated by the piston 63. This arm has at its end a spring-pressed contact plunger 92 which engages the inner surface of an arcuate insulation member 93. On the inner face of this member is theelongated contact 94. The parts are so adjusted that, when the piston is at rest due to lack of air pressure, the circuit 90 of the oil pump motor is opened and is not closed until an appreciable air pressure has built up in the chamber 15 which insures an adequate blowing-out of the burner passages prior to the feeding of oil. As soon as the oil pump starts, the magneto comes into action, and ignition is instantaneous when the valve 81 opens. It is important that ignition be subsequent to movement of air through the burner in order that residual fuel be not ignited to produce an explosion. This flow of air also insures quiet and clean ignition when the oil is injected as there is always sufiicient air available for combustion.

On stopping, it will be seen that an opening of the switch 8'7 will permit the fan to slowly come to rest, but, as the pressure falls in the chamber 15, the arm 60 moves to the left and leaves the contact 94, and, owing to the load against which it is working, the motor 83 stops almost instantly. The fan motor, however, continues to run by its momentum for a considerable period to cool the burner parts and blow out any vapors of fuel. This combination of the oil quantity regulating mechanism with the oil pump motor switch is a particularly happy one, for it provides fool-proof control which insures the proper-sequence of operations, and it also insures that ignition takes place at a low flame, for the low air pressure existing at the time of the oil pump starting effectively limits the quantity of oil which can be delivered through the nozzle.

In Figure 5 is shown a modification of the fuel control valve and associated parts in which the valve is of the simple, longitudinally movable plug type and is directly connected to the operating member.

In this figure,. the operating mechanism is again the cylinder 62 and its piston 63' or any other similar mechanism, such as a diaphragm, bellows, or the like. The piston rod 65' is extended beyond the yoke 66' and has secured to its end the enlarged plug portion 101, circular in cross section and having the tapered slabbedoff face 102. This plug is a close fit in a cylinder 103 having a port 104 at one end and a port 105 in a side and with which the plug cooperates. The pipe 50 may enter the port 104 and the pipe 56 may leave the port 105. The lever 60 is merely pivoted at 107 instead of being carried on the valve operating member, as in the preferred form. It will be obvious how this modification is used.

It will be seen that the invention is susceptible to many variations in the type of apparatus used therein and is not at all limited by the particular regulators shown nor to the particular fuel spray nozzle or thimble tube boiler, and it is intended that the invention be limited only in accordance with the appended claims. The invention, of course, can be used equally as well with gas as liquid fuels.

It has been found in practice that the device provides adequate control by using the pressure of the air supplied to the burner as a control element. The adjustments are such that the air pressure will vary automatically with the boiler pressure and also with changes in voltage of the current supplied to the fan motor. Therefore, as the quantity of oil supplied to the burner is directly controlled by the air pressure, it follows that changes in either boiler pressure or in voltage do not interfere with proper combustion, the obtaining of which is the primary purpose of the present invention.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1.'A fuel burning system comprising in combination, a source of fluid fuel, a nozzle connected to said fuel source, means to deliver air adjacent'said nozzle, an electric motor to drive said means, a starter for'said motor, means actuated by pressure of air from said delivery means to regulate the quantity of oil delivered by said nozzle, an electric driven fuel pump to supply said nozzle, a circuit for said oil pump drive means, a switch for said circuit, said switch being actuated by said air pressure actuated means only after a predetermined air pressure has been built up.

2. A fuel burning system comprising in combination, a source of fluid fuel, a nozzle connected to said fuel source, means to deliver air adjacent said nozzle, an electric motor to drive said means, a starter for said motor, means actuated by pressure of air from said delivery means to regulate the quantity of oil delivered by said nozzle, an electric driven fuel pump to supply said nozzle, a circuit for said oil pump drive means, a switch for said circuit, said switch being actuated by said air pressure actuated means only after a predetermined air pressure has been built up, ignition means for said fuel, said means being brought into operation in unison with said oil pump.

3. Control mechanism for an oil burner supplied with oil by an electric motor driven pump and with air under pressure, comprising a valve for controlling the quantity of oil delivered by the burner, means responsive to the pressure of said air to actuate said valve to control the quantity of oil, a. switch to start the oil pump motor and means associating said switch and pressure responsive means to close the switch only after predetermined air pressure is available at the burner.

4. In a fuel burner system for steam boilers, in combination, a burner nozzle for fuel, an electric motor driven fuel pump therefor, a valve to regulate the rate of oil delivery by said nozzle, a blower driven by an electric motor subject to variable voltage, means to deliver air from said blower adjacent said nozzle, a damper to regulate the flow of air, means actuated by the pressure of steam in the boiler to regulate said damper, means actuated by the pressure of the air on the burner side of said damper to regulate said oil valve, a switch for the oil pump motor, said last mentioned means closing the switch after a predetermined air pressure is available and opening it prior to cessation of air pressure whereby air is delivered first on starting and last on stopping the burner.

5. A fuel burning system for steam boilers comprising in combination a burner nozzle, a pump supplying liquid fuel to said nozzle through a'continuous fuel supply pipe, an electric motor to drive said fuel pump, a switch for the fuel pump motor, a chamber adjacent to the burner nozzle, a blower, an air supply pipe between the blower and chamber, a throttle in the air supply pipe controlled by the pressure within the boiler, the pressure in said air chamber and supply pipe on the burner side of the throttle being variable both by the throttle and due to variations in the speed of the blower, a relief pipe from the fuel supply passage to the nozzle to withdraw fuel and thereby reduce the quantity atomized, a valve in said relief pipe, means actuated in accordance with variations in the air supply pressure on that side of the throttle adjacent to the burner to move said relief valve and maintain the fuel-air ratio, the switch for the fuel pump motor being actuated by the said air pressure actuated means.

6. A fuel burning system for steam boilers comprising in combination a burner nozzle, a pump supplying liquid fuel to said nozzle through a continuous fuel supply pipe, an electric motor to drive said fuel pump, a switch for the fuel pump motor, a chamber adjacent to the burner nozzle, a blower, an air supply pipe between the blower and chamber, a throttle in the air pipe controlled by the pressure within the boiler, the pressure in said air chamber and supply pipe on the burner side of the throttle being variable both by the throttle and due to variations in the speed of the blower, a relief pipe from the fuel supply passage to the nozzle to withdraw fuel and thereby reduce the quantity atomized, a valve in said relief pipe, means actuated in accordance with variations in the air supply pressure on that side of the throttle adjacent to the burner to move said relief valve and maintain the fuel-air ratio, the switch for the fuel pump motor beingactuated by said air pressure actuated means, and fuel ignition means brought into operation synchronously with the fuel supply pump.

- 7. A fuel burning system for steam boilers comprising in combination a burner nozzle, a pump supplying liquid fuel to said nozzle through a continuous fuel supply pipe, an electric motor to drive said fuel pump, a switch for the fuel pump motor, a chamber adjacent to the burner nozzle, a blower, an air supply pipe between the blower and chamber, a throttle in the air supply pipe controlled by the pressure within the boiler, the pressure in said air chamber and supply pipe on the burner side of the throttle being variable both by the throttle and due to variations in the speed of the blower, a relief pipe from the fuel supply passage to the nozzle to withdraw fuel and thereby reduce the quantity atomized, a valve in said relief pipe, means actuated in accordance with variations in the air supply pressure on that side of the throttle adjacent to the burner to move said relief valve and maintain the fuelair ratio, and means whereby said air pressure actuated means actuates the switch for the fuel pump motor towards the closed position only when the air pressure in the air chamber has reached a predetermined value, said means stopping the fuel pump motor before the air pressure has dropped to zero.

8. A fuel burning system for steam boilers comprising in combination a burner nozzle, a pump supplying liquid fuel to the nozzle, an electric motor for driving the fuel pump, a starting and stopping circuit for said fuel pump, a chamber adjacent to said nozzle, a blower, an air supply pipe between the blower and chamber, a throttle in the air supply pipe controlled by the pressure within the boiler, the pressure in said air chamber and supply pipe on the burner side of the throttle being variable both by the throttle and due to variations in the speed of the blower, a relief pipe from the fuel supply passage to the nozzle to withdraw fuel and thereby reduce the quantity atomized, a 1

valve in said relief pipe, a lever for operating the relief valve, means operatively connected to the lever and actuated in accordance with variations in the air supply pressure on that side of the throttle adjacent to the burner to move said relief valve and maintain the fuel-air ratio, a contact on the lever electrically connected to one pole of the fuel pump motor circuit, and a segmental contact electrically connected to the other pole of the fuel pump circuit, said lever contact bearing against the segmental contact only after a predetermined air supply pressure has been reached to move the lever through an initial distance.

9. A fuel burning system for steam boilers comprising in combination a burner nozzle, a pump supplying liquid fuel to the nozzle, an electric motor for driving the fuel pump, a starting and stopping circuit for said fuel pump, a chamber adjacent to said nozzle, a blower, an air supply pipe between the blower and chamber, a throttle in the air supply pipe controlled by the pressure within the boiler, the pressure in said air chamber and supply pipe on the burner side of the throttle being variable both by the throttle and due to variations in the speed of the blower, a relief pipe from the fuel supply passage to the nozzle to withdraw fuel and thereby reduce the quantity atomized, a valve in said relief pipe, a lever for operating the relief valve, means operatively connected to the lever and actuated in accordance with variations in the air supply pressure on that side of the throttle adjacent to the burner to move said relief valve and maintain the fuelair ratio, a contact on the lever electrically connected to one pole of the fuel pump motor circuit, and a segmental contact electrically connected to the other pole of the fuel pump circuit, said lever contact bearing against the segmental contact to start the fuel pump only after a predetermined air supply pressure has been reached to move the lever through an ini-' tial distance and open the relief valve, a) fall in the air supply pressure below said predetermined value causing said lever to close the relief valve and break the fuel pump circuit to stop the motor before the air supply pressure has fallen to zero.

THOMAS CLARKSON. 

